Direct Conversion of Human Dermal Fibroblasts into Cardiomyocyte‐Like Cells Using CiCMC Nanogels Coupled with Cardiac Transcription Factors and a Nucleoside Drug

Using direct conversion technology, normal adult somatic cells can be routinely switched from their original cell type into specific differentiated cell types by inducing the expression of differentiation‐related transcription factors. In this study, normal human dermal fibroblasts (NHDFs) are directly converted into cardiomyocyte‐like cells by drug and gene delivery using carboxymethylcellulose (CMC) nanoparticles (CiCMC‐NPs). CMC‐based multifunctional nanogels containing specific cardiomyocyte‐related genes are designed and fabricated, including GATA4, MEF2C, and TBX5 (GMT). However, GMT alone is insufficient, at least in vitro, in human fibroblasts. Hence, to inhibit proliferation and to induce differentiation, 5‐azacytidine (5‐AZA) is conjugated to the hydroxyl group of CMC in CiCMC‐NPs containing GMT; in addition, the CMC is coated with polyethylenimine. It is confirmed that the CiCMC‐NPs have nanogel properties, and that they exhibit the characteristic effects of 5‐AZA and GMT. When CiCMC‐NPs‐containing 5‐AZA and GMT are introduced into NHDFs, cardiomyocyte differentiation is initiated. In the reprogrammed cells, the mature cardiac‐specific markers cardiac troponin I and α‐actinin are expressed at twofold to threefold higher levels than in NHDFs. Engineered cells transplanted into live hearts exhibit active pumping ability within 1 day. Histology and immunohistology of heart tissue confirm the presence of transplanted engineered NHDF cells at injection sites.